Drive mechanism for adjusting the rotor blades of wind power installations

ABSTRACT

A device for adjustment of rotor blades which are pivotally mounted on a rotor hub of a wind power plant, with a drive for turning the rotor blades and a lockout which is connected to each rotor blade, the lockout being an activatable lockout which in the activated state prevents turning of the rotor blades into the operating position, but allows turning of the rotor blades into the feathered position.

BACKGROUND OF THE INVENTION

Device for adjustment of rotor blades which are pivotally mounted on therotor hub of a wind power plant, with a drive for turning the rotorblades and with a lockout which is connected to the rotor blades.

DESCRIPTION OF THE RELATED ART

Wind power plants are plants which are exposed to high stresses. Onemethod of reducing the forces acting on the plant is to use rotor bladeadjustment. In addition to the effect of reducing the load, rotor bladeadjustment can also be used as a braking system by turning the rotorblades in the direction of the feathered position to shut down the windpower plant and thus the plant loses power and rpm.

Basically the rotor blades, if they are not stopped, have the tendencyto turn due to inertial forces and forces of gravity (the center ofgravity of the rotor blades is outside their axis of rotation) andexternal wind forces. The wind forces cause turning of the rotor bladesin the direction of the feathered position and the inertial forces causeturning in both directions according to the respective position of therotor blades during one rotor revolution, the inertial forces mostlypredominating.

Turning of the rotor blades beyond the feathered position isconventionally limited by a mechanical stop. If therefore the rotorblades are not stopped, they execute an oscillating rotary motion aroundtheir axis of rotation over the course of one rotor revolution, by whichthe wind power plant cannot be stopped due to wind forces.

In plants according to the prior art which for the most part have threerotor blades, the latter are usually adjusted by a central linear drivein combination with a mechanical rod. Newer systems usemechanical/electrical and mechanical/hydraulic individual bladeadjustment. In these systems each rotor blade is adjusted individuallyand by means of a control unit synchronism of rotor blade adjustment isaccomplished. The advantage of individual blade adjustment is that whena drive unit fails the remaining drive units can still be used to turnthese rotor blades into the feathered position in order to reliably shutdown the plant.

To ensure braking of the plant by rotor blade adjustment even when thepower supply fails, in plants of the prior art it is equipped forexample with emergency battery power supply or the rotor blades aremoved into the working position against a spring force or hydraulicpressure, with which reset of the rotor blades into the featheredposition is ensured in any case. Equipping the rotor blade adjustmentwith an emergency battery power supply is associated with relativelyhigh costs, since the batteries necessary for turning the rotor bladesinto the feathered position or keeping them in the feathered positionuntil the plant stops must have a not inconsiderable power or capacity.

In the case of adjusting the rotor blades against spring force orhydraulic pressure, correspondingly complex mechanical and hydraulicdevices are necessary, and rotor blade adjustment must also be designedfor higher loads since the spring force or the force of hydraulics mustalso be overcome.

U.S. Pat. No. 4,653,982 discloses a wind power plant with a genericadjustment means for rotor blades in which the rotor blades, whenreaching a certain maximum rotor rpm, supported by an electromagnet areturned into the feathered position and kept in this position until therotor rpm again drops below a certain rpm and the rotor blades againturn automatically into the operating position.

U.S. Pat. No. 4,701,104 discloses an adjustment means with a lockout forthe rotor blades of a ram-air turbine in which the lockout is kept openby an electromagnet during turbine operation. When the lockout isactivated by interruption of the power supply to the electromagnet, therotor blades are turned into the feathered position by the adjustmentmeans and kept in this position.

U.S. Pat. No. 5,452,988 discloses a gas turbine fan with rotor bladeadjustment which has an adjustment means for turning the rotor bladesinto the operating or feathered position and for stopping the rotorblades in the position which has been set at the time.

SUMMARY OF THE INVENTION

The object of the invention is to make available rotor blade adjustmentin which turning of the rotor blades into the feathered position whenthe power supply fails is possible with less technical effort.

The lockout is deactivated in normal operation and when the power supplyfails it is activated, by which the rotor blades can only continue toturn into the feathered position and are held there until the plant hascome to a standstill.

BACKGROUND OF THE INVENTION

Other features and advantages of the invention follow from the dependentclaims and the following description of embodiments of the inventionwith reference to the drawings.

FIGS. 1 and 2 show two embodiments of rotor blade adjustment means as inthe prior art,

FIG. 3 shows one embodiment of rotor blade adjustment as claimed in thisinvention,

FIG. 4 shows one embodiment of the backstop from FIG. 3,

FIG. 5 shows another embodiment of the backstop from FIG. 3, and

FIG. 6 shows one embodiment of rotor blade bearing and of a rotor bladein order to achieve an increased restoring moment of the rotor blades.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows the embodiment of rotor blade adjustment which is used mostoften in wind power plants. One rotor blade 1 is attached to an innerring of a pivot bearing 2. For reasons of clarity only one rotor blade 1is drawn. Conventionally however there is more than one rotor blade 1,generally three rotor blades 1. The outer ring of this pivot bearing 2is screwed to a rotating rotor hub 3. By means of a mechanical rod 4 thelinear motion of a connecting rod 5 is converted into rotary motion ofthe rotor blades 1. The connecting rod 5 which corotates with the rotoris supported in a rotor shaft 6 and gearing 7. A hydraulic cylinder 8which does not turn delivers linear motion against the force of a spring9 into the connecting rod 5, one thrust bearing 10 decoupling therotating connecting rod 5 from the nonrotating components such as thespring 9 and the hydraulic cylinder 8 in the direction of rotation. Whenthe power supply of the plant fails, the rotor blades 1 are turned bythe spring 9 via the rods 4, 5 into the feathered position.

FIG. 2 shows another embodiment of rotor blade adjustment of the priorart. The rotor blade 1 is attached to pivot bearings 11 with internaltoothing. The outer ring of this pivot bearing 11 is screwed to therotating rotor hub 3. A geared motor 12 with a pinion 13 which turns therotor blade 1 is assigned to each rotor blade 1. Each geared motor 12 istriggered via one converter 14 at a time. The power is supplied innormal operation for all drive units via a line 15 and a slipring 1. Acontrol unit 18 ensures synchronism of the rotor blades 1. In the caseof failure of this power supply each converter 14 is supplied separatelyfrom the emergency battery power supply 17, by which the rotor blades 1can also be moved into the feathered position in this case.

FIG. 3 shows a first embodiment of a rotor blade adjustment as claimedin the invention. The rotor blade 1 is, as known, attached to a pivotbearing 2 with inner toothing 11. The outer ring of this pivot bearing 2is screwed to the rotating rotor hub 3. By means of the geared motor 12and the pinion 13 each rotor blade 1 (conventionally three rotor blades)is turned separately. Each geared motor 12 is triggered via oneconverter 14 at a time. Power is supplied for all drive units via a line15 and the slipring 16. When this power supply fails, a lockout 19 whichis connected to the geared motor 12 causes the rotor blades to be ableto turn only in the direction of the feathered position.

FIG. 4 shows a first embodiment of the lockout 19 as claimed in theinvention from FIG. 3, made as a backstop. The geared motor 12 hasgearing 20, a stator 21 and a rotor with an elongated rotor shaft 22.The backstop 19 has a housing 23 which is permanently connected to thestator 21 and a bottom part 24 of a free wheel, the part beingpermanently connected likewise to the stator 21. The top part 41 of thefree wheel has a coupling part 25 with a brake lining 26 on the sidefacing away from the bottom part 24. The coupling part 25 is freelyturning and is supported to be able to move axially on the rotor shaft22. The coupling part 25 and the bottom part 24 on the sides facing oneanother have a sawtooth-like profile 38 which allows mutual rotation inonly one direction. The top part 41 furthermore has a brake disk 27which is connected likewise with an axial displacement capacity buttorsionally strong to the rotor shaft 22. The rotor shaft 22 has aplate-shaped end 28. One spring 29 is pretensioned under pressurebetween the plate-shaped end 28 and the brake disk 27. For rotor bladeadjustment in normal operation the brake disk 27 is raised from thebrake lining 26 by an electromagnet 30 against the force of the spring29, by which the geared motor 12 can turn freely in both directions. Itis also fundamentally conceivable for the brake disk 27 and the brakelining 26 to be omitted and the spring 29 to press on the coupling part25 and for the coupling part 25 to be attracted directly by theelectromagnet 30. The coupling part 25 must then of course be connectedtorsionally strong to the shaft 22.

When the power supply fails the electromagnet 30 is automaticallydeactivated, by which the brake disk 27 is pressed by the force of thespring 29 against the brake lining 26 so that the coupling part 25 ofthe free wheel is connected torsionally strong to the rotor shaft 22. Bymeans of the sawtooth-like profile 38 of the coupling part 25 and of thebottom part 24 of the free wheel and by the displacement capacity of thecoupling part 25 which is axial against the force of the spring 29, therotor shaft 22 of the motor 12 and as a result of the rotor blade 1 canonly continue to turn in the direction of the feathered position as faras a mechanical stop.

FIG. 5 shows another embodiment of the backstop from FIG. 3 as claimedin the invention. The geared motor 12 in turn has gearing 20, a stator21, and a rotor with an elongated rotor shaft 22. The lockout 19 has ahousing 23 which is permanently connected to the stator 21 and a bottompart 24 which is permanently connected likewise to the stator 21 and towhich a brake lining 31 is attached. The brake disk 27 which forms thetop part 41 of the lockout is likewise connected to the rotor shaft 22with an axially displacement capacity and in a torsionally strongmanner. The rotor shaft 22 has a plate-shaped end 28 and the spring 29is pretensioned under pressure between the plate-shaped end 28 and thebrake disk 27. In normal operation the electromagnet 30 lifts the brakedisk 27 from the brake lining 26 against the force of the spring 29, bywhich the geared motor 12 can turn freely in both directions. In case ofdeactivation of the electromagnet 30 the brake disk 27 is pressed by theforce of the spring 29 against the brake lining 31, with which it or thestator 21 is connected torsionally strong to the rotor shaft 22, bywhich the rotor shaft 22 is prevented from turning. The electromagnet 30of the lockout of each individual geared motor 12 is supplied separatelywith power and is also individually activated by means of a controlunit. When the power supply for the geared motors fails, during rotationof the rotor the electromagnet 30 is activated and thus the brake disk27 is raised off the brake lining 31 only in the area in which the rotorblades, due to the combination of the external wind forces and inertialforces, move in the direction of the feathered position. This results inthat the rotor blades move only in the direction of the featheredposition and thus continuous braking of the rotor takes place. For powersupply of the electromagnets 30 and the control, in this case there isan emergency power supply in the form of a battery 17 which in any casedue to the relatively small power demand can be smaller than the battery17 in the prior art in which the battery 17 must deliver energy for theactive rotation of the rotor blades 1 into the feathered position andfor holding of the rotor blades 1 in this position until completestandstill of the plant.

In one embodiment of the invention it can also be provided that one(provided anyway in the embodiment of FIG. 5) a battery 17 be used toturn the rotor blades 1 at least partially, for example by 10 to 20°,from the operating position in the direction of the feathered positionin order to prevent braking as fast as possible or in strong wind guststo prevent further acceleration of the rotor. At the same time, in theembodiment of FIG. 4 the backstop 19 is activated and prevents the rotorblades 1 from then turning back into the operating position. In theembodiment from FIG. 5, after this turning of the rotor blades 1 bypreferably 10 to 20°, depending on whether the inertial forces causeturning into the feathered position or not, the lockout 19 is kept openor activated.

Instead of the described brake linings 26, 31 which are shown and whichinteract with a brake disk 27 of course also there can be form-fittedconnection means such as for example claw couplings, by which the spring29 and accordingly also the electromagnet 30 can be made weaker.

FIG. 6 shows embodiments of the rotor blade support and the rotor bladein the feathered position with which an increased restoring moment ofthe rotor blades 1 can be achieved. The rotor blade 1 is attached to apivot bearing 32. The outer ring of this pivot bearing 32 is screwed tothe turning rotor hub 3. The pivot bearing 32 has a screw-down surfacefor the rotor blades 1 which is slightly sloped relative to thescrew-down surface to the rotor hub 3 (roughly 1 to 2°). Thus the pivotbearing 32 is likewise sloped by this angle α. This results in that theforce vector 35 which results due to the outer wind forces attacksoutside the axis 34 of rotation, by which additional torque 36 aroundthe axis 34 of rotation acts in the direction of the feathered position.

Alternatively or additionally, on the end edge of the rotor blades 1 anadditional weight 37 can be attached which also causes additional torquearound the axis 34 of rotation which, depending on the position of therotor blade 1 during one rotor revolution, causes turning in thedirection of the working position or the feathered position. Since whenthe power supply fails the lockout allows only turning of the rotorblades 1 in the direction of the feathered position and blocks theopposite direction, these measures cause accelerated turning of therotor blades 1 in the direction of the feathered position and thusaccelerated braking of the rotor.

What is claimed is:
 1. A device for adjustment of rotor blades (1) whichare pivotally mounted on a rotor hub (3) of a wind power plant, with adrive for turning the rotor blades (1) and a lockout (19) which isconnected to the rotor blades (1), wherein the lockout is an activatablelockout (19) which in the activated state prevents turning of the rotorblades (1) into the operating position, but allows turning of the rotorblades into the feathered position, and one lockout (19) is assigned toeach rotor blade (1).
 2. A device as claimed in claim 1, wherein thelockout (19) is a backstop which prevents turning of the rotor blade (1)into the operating position.
 3. A device as claimed in claim 1, whereinthe lockout (19) is assigned to the drive (12) for the rotor blade (1).4. A device as claimed in claim 1, wherein the lockout (19) has a part(24) which is connected to the rotor hub (3) and a part (41) which isconnected to the rotor blade (1), which parts are connected to oneanother to prevent turning of the rotor blade (1).
 5. A device asclaimed in claim 4, wherein the part (41) of the lockout (19) connectedto the rotor blade (1) is connected torsionally strong to the rotorshaft (22) of the drive (12).
 6. A device as claimed in claim 4, whereinthe part (24) of the lockout (19) connected to the rotor hub (3) ispermanently connected to the stator housing (21) and wherein the part(41) which is connected to the rotor blade (1) is supported to be ableto move axially on the rotor shaft (22).
 7. A device as claimed in claim4, wherein the part (41) which is connected to the rotor blade (1) andthe part (24) which is connected to the rotor hub (3) are connected toone another by form-fitting.
 8. A device as claimed in claim 7, whereinon the sides of the part (41) which is connected to the rotor blade (1)and of the part (24) which is connected to the rotor hub (3), i.e. thesides assigned to one another, there is a roughly sawtooth-shapedprofile (38) which are engaged to one another.
 9. A device as claimed inclaim 7, wherein the part (41) which is connected to the rotor blade (1)has a brake disk (27) which is connected torsionally strong to the rotorshaft (22) and has a coupling part (25) which has an essentiallysawtooth-shaped profile (38) on the side facing the part (24) connectedto the rotor hub (3) and has a brake lining (26) on the side facing thebrake disk (27) and wherein the coupling part (25) is supported on therotor shaft (22) to be able to turn and to move axially.
 10. A device asclaimed in claim 4, wherein the part (41) which is connected to therotor blade (1) and the part (24) which is connected to the rotor hub(3) are connected to one another by frictional engagement.
 11. A deviceas claimed claim 4, wherein there is a means (30) to detach the part(41) which is connected to the rotor blade (1) and the part (24, 31)which is connected to the rotor hub (3) from one another and wherein thepart (41) which is connected to the rotor blade (1) are pressed by theforce of a spring (29) continually in the direction to the part (24)which is connected to the rotor hub (3).
 12. A device as claimed inclaim 11, wherein the means (30) to detach the part (41) which isconnected to the rotor blade (1) and the part (24, 31) which isconnected to the rotor hub (3) from one another is an electromagnet. 13.A device as claimed in claim 12, wherein there is an emergency powersupply (17) in the form of a battery which is intended for turning therotor blades (1) into the feathered position and optionally foractivating the electromagnet (30).
 14. A device as claimed in claim 11,wherein the spring (29) on the one hand is supported on the part (41)which is connected to the rotor blade (1) and on the other hand on aprojection (28) on a rotor shaft (22) of the drive (12).
 15. A device asclaimed in claim 4, wherein the part (41) which is connected to therotor blade (1) has a brake disk (27).
 16. A device as claimed in claim15, wherein on the part (24) which is connected to the rotor hub (3)there is a brake lining (31) on the side facing the brake disk.
 17. Adevice as claimed in claim 4, wherein the part (24) of the lockout (19)connected to the rotor hub 93) is permanently connected and wherein thepart (41) which is connected to the rotor blade (1) is supported to beable to move axially on the rotor shaft (22).
 18. A device foradjustment of rotor blades (1) which are pivotally mounted on a rotorhub (3) of a wind power plant, with a drive for turning the rotor blades(1) and a lockout (19) which is connected to the rotor blades (1),wherein the lockout is an activatable lockout (19) which in theactivated state prevents turning of the rotor blades (1) into theoperating position, but allows turning of the rotor blades into thefeathered position, and the longitudinal axis (33) of the rotor blade(1) is sloped towards the axis of rotation (34) of the rotor blade (1).19. A device as claimed in claim 18, wherein the rotor blade (1) isconnected via a pivot bearing (32) to the rotor hub (3), the end face(39) of the outer ring of the pivot bearing (32) which is connected tothe rotor hub (3) being sloped at an angle (a) to the end face (40) ofthe inner ring of the pivot bearing (32) which is connected to the rotorblade (1).
 20. A device for adjustment of rotor blades (1) which arepivotally mounted on a rotor hub (3) of a wind power plant, with a drivefor turning the rotor blades (1) and a lockout (19) which is connectedto the rotor blades (1), wherein the lockout is an activatable lockout(19) which in the activated state prevents turning of the rotor blades(1) into the operating position, but allows turning of the rotor bladesinto the feathered position, and an additional weight (37) is attachedto the rotor blade (1).
 21. A device as claimed in claim 20, wherein theadditional weight is added on an end edge of the rotor blade.